Rigid-Flex PCB Array Interconnection Redundancy

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Solution Overview

Problem

Existing printed circuit boards (PCBs) face reliability issues due to mechanical stress, moisture, and corrosion, particularly in applications requiring flexibility and conformity to curved surfaces, leading to frequent failures in interconnections and system malfunctions.

Innovation Solution

A 3D bendable PCB technology with redundant interconnections is developed, allowing arrays of rigid PCBs to be electrically interconnected without wires or connectors, ensuring continued functionality even if individual connections fail, and is resistant to mechanical damage and moisture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If rigid PCBs are used to provide mechanical support and electrical interconnections, then structural strength and electrical reliability are improved, but flexibility and adaptability to curved surfaces deteriorate

Engineering Contradiction:

Improvestructural strengthVSAvoidflexibility

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The system divides the PCB into multiple rigid PCBs connected by flexible PCBs, allowing each rigid unit to provide structural strength while the flexible connectors provide adaptability. This segmentation enables the overall system to conform to curved surfaces while maintaining the mechanical strength of rigid PCBs.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention merges rigid PCBs with flexible PCBs into a hybrid rigid-flex PCB array, combining the advantages of both rigid structures (strength, electrical reliability) and flexible connectors (adaptability, flexibility) to resolve the contradiction between these properties.

Inventive Principle:

Principle #5Merging (Combining)

2Device complexity

If single interconnection paths are used between rigid PCBs, then device complexity is reduced, but reliability deteriorates due to single point of failure

Engineering Contradiction:

Improveinterconnection complexityVSAvoidconnection reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The system implements redundant interconnections selectively at critical locations where reliability is most needed, rather than uniformly across all connections. This localized approach to redundancy maintains overall system simplicity while improving reliability at vulnerable points.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Multiple redundant interconnection paths are pre-established between rigid PCBs to compensate for potential future failures. This beforehand cushioning ensures that if one connection fails, alternative paths maintain system operation, thereby improving reliability without requiring complex real-time failure detection and switching mechanisms.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Adaptability or versatility

If flexible PCBs are used to enable bending and conformability, then adaptability to curved surfaces is improved, but mechanical strength and resistance to mechanical stress deteriorate

Engineering Contradiction:

ImproveconformabilityVSAvoidmechanical strength

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The system segments the PCB into rigid units that maintain mechanical strength and flexible connectors that provide conformability. The rigid PCBs handle mechanical stress locally, while flexible PCBs accommodate bending and shaping, distributing mechanical loads appropriately across the system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses composite construction combining rigid PCB materials with flexible PCB materials to create a hybrid structure that simultaneously achieves both mechanical strength and conformability, leveraging the complementary properties of different materials.

Inventive Principle:

Principle #40Composite materials

4Reliability

If redundant interconnections are implemented, then reliability is improved, but manufacturing complexity and cost increase

Engineering Contradiction:

Improvesystem reliabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system implements redundancy at strategic locations rather than universally throughout the entire PCB array. This partial redundancy approach provides sufficient reliability improvement while avoiding the excessive complexity and cost of complete redundancy in all connections.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS11184981B2Method of supplying electrical power from rigid printed circuit board to another rigid printed circuit board in rigid-flex printed circuit board array

Publication Date: 2021.11.23 ADVENTIVE IPBANK SARL

AI summary

A rigid-flex PCB includes an array of rigid PCB “islands” interconnected by a flexible PCB formed into flexible connectors. The conductive and insulating layers of the flexible PCB extend into the rigid PCBs, giving the electrical connections to the rigid PCBs added resistance to breakage as the rigid-flex PCB is repeatedly stressed by bending and twisting forces. In addition, the durability of the rigid-flex PCB is enhanced by making the power and signal lines driving the rigid PCBs redundant so that a breakage of a line will not necessarily affect the operation of the rigid PCB to which it is attached. The rigid-flex PCB is particularly applicable to light pads used in phototherapy, wherein LEDs mounted on the rigid-PCBs are powered and controlled through the redundant lines in the flexible PCB.